Process for inhibiting corrosion in oil wells



Patented Oct. 21, 1952 UNITED I rue-s1 PROCESS FOR INHIBITING CORROSIONIN. I OIL WELLS Delaware ,No Drawing. Application April 3, 1950, SerialNo. 153,768

The present invention is directed to a method for inhibiting thecorrosiveness to. corrodible metal surfaces of corrosive subsurfacefluids containing carbon dioxide. vMore particularly, .the inventionrelates to a method for inhibiting the corrosivity of petroliferous wellfluids containing carbon dioxide to corrodible ferrous metal conduitsand attendant equipment through which the fluids are flowed andprocessed.

In many oil fields and gas-condensate flelds,

12 Claims. (Cl. 252-855) the production of fluids from subsurfaceformations is accompanied by extremely severe corrosion of the conduitsand attendant equipment which is contacted by the fluid mixture beingproduced. In many cases it is found that the fluid mixture is acidic innature and contains substantial amounts of carbon dioxide, a portion ofwhich dissolves in water present in the fluids to form carbonic acid.These fluids, including the carbon dioxide, originate in the subsurfaceformations. In some cases the corrosion occurs throughout the conduitsand attendant equipment through which the fluids are flowed andprocessed while in other cases the corrosion is limited primarily torather restricted areas of the conduit and is often particularly severein that portion of the conduit adjacent the well head. If corrosion,whether intensive or extensive, is permitted to continue unabated, theconduit and attendant equipment will become sufliciently damaged torequire replacement. Not only is the actual cost of such replacementhigh, but other factors may be involved which further increase costs.For example, it may be necessary to kill a high pressure Well in orderto make the necessary replacements. placements and repairs are beingmade, there is a loss in revenues due to having the well off production.Even of more importance than the high costs incurred as a result ofcorrosion, is the danger that a well will flow wild as a'result of thefailure of the conduit or equipment due to corrosion. Such a result maybe catastrophic.

It is therefore the main object of the present invention to provide amethod whereby corrosion Furthermore, while re- 2 range of 300 to 550F.preferab1y in the presence of an alkaline reacting catalyst.

Fatty acids which may suitably be used as the fatty material in theaforementioned reaction include those fatty acids having at least 12 andno more than 26'carbon atoms per molecule. As examples of such acids,mention may be made of oleic, ricinoleic, linoleic, linolenic, licanic,eleostearic, arachidonic, clupanodonic, lauric, myristic, arachidic,stearic palmitic, etc. The fatty oils which may be employed are thosefrom which fatty acids having from 12 to 26 carbon atoms in the moleculecan be derived. Fatty. oils which have been found to produce especiallyeffective agents include tung oil, China-wood oil, oiticica oil,chaulmoogra oil, cottonseed oil, menhaden oil, linseed oil, castor oil,and the like. It will be understood, of course, that mixtures ofindividual members of the aforementioned class of oilsor mixtures of theindividual members of the afore-' mentioned class of acids or mixturesincluding both oils and acids may be employed as the fatty material fromwhich the corrosion inhibiting agent of thepresent invention isproduced.

Various alkyl and/ or 'alkanol amines may suitably be employed'in theaforementioned reaction to produce the corrosion inhibiting reaction.product of the present invention. Examples of of corrodible ferrousmetal surfaces by corrosive well fluids containing carbon dioxide issubalkanol amines which may be employed include triethanol amine,di-n-propanol amine, di-isoboth alkanol and alkyl groups. Examples ofsuch alkyl-alkanol amines include di-ethyl,ethanol amine;ethyl,di-ethanol amine; ethyl,di-npropanol amine; di-ethyl,n-propanolamine;

ethyl,di-isopropanol amine; di-ethyLisopropanol amine;n-propyl,di-ethanol amine; isopropyLdiethanol amine; di-n-propyl,ethanolamine; di-

. isopropyl,ethanol amine; ethyl,di-butanol amine;

alkyl or alkanol amine at a temperature in the etc. While the aminesemployed'preferably contain a total of betweenfi and 18 carbon atoms inthe alkyl and/or alkanol side chains, they may contain an evenlargernumberof carbon atoms in the side chains.

1 course, that mixtures of the. aforementioned It will be understood, of

cQF-FKCE amines may suitably be employed. Polymers of these amines,--such as the polymers of tri-ethanol amine, may also suitably beemployed.

When the fatty derivatives of the present invention are prepared'from afatty oil, it is pref-,- erable that the fatty oil be present in theinitial reaction mixture in a weight ratio of from about 1:1 to about5:1 as compared to the alkyl or alkanol amine. When the fatty derivativeis prepared from a fatty acid, the fatty acid is preferably present inthe initial reaction mixture in a weight ratio of from about 0.5:1 toabout 3:1 as compared to the amine.

The effectiveness as a corrosion inhibiting agent of the reactionproduct of fatty oils and/ or fatty acids with alkyl amines and/oralkanol amines depends upon the temperature at which the reaction isconducted. .If the reaction is conducted at a temperature below about300 R, the resulting reaction product possesses little, if any,effectiveness as a' corrosioninhibiting agent for gaseoondensate -Iwellfluids containing. carbon dioxide. .On the other handyif the reaction isconducted at a temperature in excess of about 550 the reaction productobtained tends to be of very high solidification point and .of lowsolubility in the corrosive media. The reaction temperature selectedwill depend to some extent upon the particular fatty oil or acidemployed and upon the particular amine employed. For example, when thecorrosion inhibiting agent is prepared from triethanol amine and eithertung oil, oiticica .oil, chaulmoogra oil, or, cottonseed oil in thepresence of sodium hydroxide, a reaction temperature maintained for 2m4.- hours in the range of 400 to 475 F. results in a product ofespecially desirable inhibition properties.

The extent of reaction, in addition to depending upon reactiontemperature, also depends upon the time during which the reactiOn ispermitted to continue. Ordinarily, effective agent may be prepared whenthe reactants are maintained at a temperature in the aforementionedrange for a period of time in the range of from /2 t hours, a though thepre er ed time is in the ran e of 1 /2 to 4 hours.

As h ei bef men i ned an a ka n each ing catalyst, such as alkali metalhydroxides or carbonates, or mixtures thereof, is preferably employed.The fatty acids and amines will react to form the desired productwithoutthe aid of a catalyst; the fatty oils, however, require the useof a catalyst to accelerate the reaction betweenthe oil and the amine.Examples of alkaline reacting catalysts are sodium hydroxide and sodiumcarbonate. The alkaline reacting catalyst concentrations ordinarily neednot exceed about 3% by weight of the reactants although considerablylower concentrations may be successfully employed. For example, aconcentration of 0.5% by weight of sodium hydroxide or sodium carbonatebased upon the weight of the reactants has been found sufiicient topromote the. reaction. As a matter of fact, as little as about 0.05% ofsodium hydroxide based upon the weight of the reactants has been foundsuflicient- The amount of fatty derivatives of the present inventionemployed toinhibit-the corrosion of ferrous metal surfaces by well fluidmixtures including moisture and carbon dioxide may be varied over arelatively wide range. However, it has been found that amounts withinthe range of 0.005% to 0.1% by volume of the fluid mixture givesatisfactory results. Ordinarily, an amount within the range of 0.005%to 0.01% by volume will be sufficient.

When it is desired to protect from corrosion th conduit in the boreholeas well as the attendant equipment, the fatty derivative or a solu--tion thereof may be injected into the borehole 7 adjacent the subsurfaceformation from which the corrosive fluid, including carbon dioxide, isproduced. Alternatively, the fatty derivative may be introduced directlyinto the conduit. A still further method of introducing the fatty de-'rivative into the fluids produced from the .subsunface formationinvolves introducing the fatty de-i rivative or a solution thereof intothe annula space betweenthe casing and the tubing. Another method ofintroducing the fatty derivative. into the subsurface fluid consists ofinjecting the fatty derivative ora solution thereof into the subsurfacereservoir through an adjacent well.

' Irrespective of the particularprocedure employed in introducing thefatty derivatives into the fluids in the well, the fatty derivativesuppresses the] corrosivity of the fluids, thereby eliminating orreducing dama eto the conduit through which the fluids are produced andto attendant equip, ment through which the fluids are flowed.

The followingexamples will illustrate the elf-- fectiveness of thecorrosion inhibitors hereinbefore described in inhibiting thecorrosivityof a corrosive condensate Well fluid containing car-.

bon dioxide to corrodible ferrous metal surfaces.

EXAMPLE I product thus formed, 0.001 volume per cent was added to abeaker containing 200 cc. of corrosive Water from the gas-condensatefield at Katy, Texas. This beaker, together with another beakercontaining 200 cc. of water from the gascondensate field at Katy, Texas,placed in a desiccator: A mild carbon steel coupon was sub-' merged inthe water in each of the beakers. The desiccator was then evacuated andcarbon di oxide was added to the desiccator to a pressure of 1 m he Eaof the, coupons was reov f m th de ccato f r .2 da s, exposure under theaforementioned conditions and the extent of the corrosion of eachcouponwas a determined by measuring the loss inweight of the coupons. Theresults'of the tests are shown a in the following table:

Table I -Qonc. of Corrosion I Percent Inhibitor Inhibitor Rat'e'ofgrease i Vol. Per Coupons tion Over cent InJXr. Blank None ReactionProdu' or" 'Iri 9 0077 ethanolamine, Tun Oil, and e el i 1 .0. 0009 89,-J g m rm EXAMPLE II 35 grams of tung oil, 30 grams of triamylamine, and2 grams of sodium hydroxide were heated together at a temperature of 392to 432 F. for a period of 2 hours. The resulting reaction prodnot, whencooled, solidified at a temperature of 244 F. The eflectiveness of thisreaction product I as an inhibitor was tested in the laboratory by usinga concentration of 0.01 weight per cent in a 50:50 mixture of brine andcondensate saturatedwith carbon dioxide. The brine and condensate wereobtained from the gas-condensate field located at Katy, Texas. 100cc. ofthe aforementioned oil-brine mixture containing the inhibitor wereplaced in a sealed glass tube and a mild carbon steel coupon wassuspendedjin' the tube. The coupon was immersed in the brineoil mixture31 times per minute for a period of 14 days. The extent of the corrosioninhibition obtained was compared with results obtained when similarcoupons were exposed under identical conditions to a carbon dioxidesaturated 50:50 mixture of brine and condensate obtained from the Katyfield, this last mentioned mixture containing no inhibitor. The resultsobtained are shown in Table II below:

The foregoing examples demonstrate the effectiveness of the inhibitingagent of the present invention in substantially eliminating thecorrosivity of condensate well fluids containing carbon dioxide tocorrodible ferrous metal surfaces.

Having fully described the present invention, what I desire to claim asnew and useful and to secure by Letters Patent is:

1. A method for reducing the corrosiveness to corrodible ferrous metalof a corrosive petroliferous well fluid including moisture and carbondioxide which comprises introducing into said fluid a corrosioninhibiting amount of the reaction product of a fatty material selectedfrom the group consisting of fatty acids having no less than 12 and nomore than 26 carbon atoms per molecule and a fatty, oil containing fattyacid radicals having noless than 12 and no more than 26 carbon atomswith an amine selected from the group consisting of alkyl and alkanolamines having a total of no less than 6 carbon atoms in the molecule,the reaction product being formed at a temperature in the range of 300to 550 F. and in the presence of an alkaline reacting catalyst selectedfrom the group consisting of alkali metal hydroxide and alkali metalcarbonate, the weight ratio of fatty material to amine being in therange of 0.5:1 to about 5.0:1.

2. A method for reducing the corrosiveness to corrodible ferrous metalof a corrosive petroliferous well fluid including moisture and carbondioxide which comprises introducing into said fluid a corrosioninhibiting amount of the reaction product of a fatty material selectedfrom the group of fatty acids having no less than 12 and no more than 26carbon atoms per molecule and a fatty oil containing fatty acid radicalshaving no less than-1'2 andno morethani26 car bon atoms with an amineselected from the group consisting of alkyl and alkanol amines having: atotal of no less than fi and no more than-18 carbon atoms per molecule,the reaction product being formed byheating the-reactants for a periodof from to 5 hours at a temperaturein the range of 300 to 550 F. in thepresence of an alkaline reacting catalyst selected'from the groupconsisting of alkali metal hydroxide and alkali metal carbonate, theweight ratio of fatty material to amine being in the range of 0.5:1 toabout 5.0:1.

3. A method in accordance with claimi ldn which the reaction product isadded to the corrosive fluid in an amount in the range of 0.005%

v to 0.1 by volume of the fluid.

4. A method in accordance with claim 2 in which the reaction product isadded to the corrosive fluid in an amount in the range of.0.005% to 0.1%by volume of the fluid.

5. A method for reducing the corrosiveness to corrodible ferrous metalof a corrosive petroliferous well fluid including moisture and carbondioxide which comprises introducing into said fluid a corrosioninhibiting amount of the reaction product formed by heating a mixture oftung oil and triethanol amine at a temperature in the range of 300 to550 F. for a period of from /g to 5 hours in the presence of an alkalinereacting catalyst selected from the group consisting of alkali metalhydroxide and alkali metal carbonate, the weight ratio of 'tung oil totri-ethanol amine being in the range of l :1 to about 5:1.

6. A method in accordance with claim 5 in which said reaction product isadded to the corrosive fluid in an amount in the range of 0.005% to 0.1by volume of the fluid.

7. A method for reducing the corrosiveness to corrodible ferrous metalof a corrosive petroliferous well fluid including moisture and carbondioxide which comprises introducing into said fluid a corrosioninhibiting amount of the reaction product formed by heating a mixture of/2 to5 hours in the'presence of an alkaline reacting catalyst selectedfrom the group consist ing of alkali metal hydroxide and alkali metalcarbonate, the weight ratio of tung oil to triamyl amine being in therange of 1:1 to about 5 1. g 8. A method in accordance with claim 7 inwhich the reaction product is added to the corrosive fluid in an amountin the range of 0.005% to 0.1% by volume of the fluid. v

9. A method for reducing the corrosiveness to corrodible ferrous metalof a corrosive petroliferous well fluid including moisture and carbondioxide which comprises introducing into said fluid a corrosioninhibiting amount of the reaction product formed by heating a mixture ofcottonseed oil and triethanol amine at a temperature in the range of 300to 550 F. for a period from to 5 hours in the presence of an alkalinereacting catalyst selected from the group consistwhich the reactionproduct is added to the corrosive fluid in an amount in the range of0.005% to 0.1% by volume of the fluid.

11. A method for reducing the corrosiveness to corrodible ferrous metalof a corrosive petrolifer- 7 OusrWelLfluid .includingmoistuwand lcarbpndie. oxide which comprises i introducing. into, ,said fiuid' a.corrosion inhibiting amount of the reaction product formed by 1heating a,.mixture of menhaden oil and triethanol amine at a temperaturein therange of 300 to'550 F. for, a period of from to 5 hours in the presenceof an alkaline reacting catalyst selectedfrom the group; consisting vofalkali metal hydroxide and alkali metal carbonate, the weight ratio ofmenhaclen oilto tri-ethanol amine being in the range ofizltoabout'a:1'.-;

12. A method in accordance with claim 11 in which the reaction productis added to the corrosive fluid inan amount in the range of10.005%tea-01% by volume of the fluid. v.

' MELBA L. LYTLE.

REFERENCES CITED 1 The following references are of record in the file ofthis patent:

mercial Solvents Corp.

1. A METHOD FOR REDUCING THE CORROSIVENESS TO CORRODIBLE FERROUS METALOF A CORROSIVE PETROLIFEROUS WELL FLUID INCLUDING MOISTURE AND CARBONDIOXIDE WHICH COMPRISES INTRODUCING INTO SAID FLUID A CORROSIONINHIBITING AMOUNT OF THE REACTION PRODUCT OF A FATTY MATERIAL SELECTEDFROM THE GROUP CONSISTING OF FATTY ACIDS HAVING NO LESS THAN 12 AND NOMORE THAN 26 CARBON ATOMS PER MOLECULE AND A FATTY OIL CONTAINING FATTYACID RADICALS HAVING NO LESS THAN 12 AND NO MORE THAN 26 CARBON ATOMSWITH AN AMINE SELECTED FROM THE GROUP CONSISTING OF ALKYL AND ALKANOLAMINES HAVING A TOTAL OF NO LESS THAN 6 CARBON ATOMS IN THE MOLECULE,THE REACTION PRODUCT BEING FORMED AT A TEMPERATURE IN THE RANGE OF 300*TO 550* F. AND IN THE PRESENCE OF AN ALKALINE REACTING CATALYST SELECTEDFROM THE GROUP CONSISTING OF ALKALI METAL HYDROXIDE AND ALKALI METALCARBONATE, THE WEIGHT RATIO OF FATTY MATERIAL TO AMINE BEING IN THERANGE OF 0.5:1 TO ABOUT 5.0:1.